Embodiments of the inventive concept relate generally to semiconductor memory devices. More particularly, embodiments of the inventive concept relate to nonvolatile semiconductor memory devices and systems, and related methods of operation.
Semiconductor memory devices can be roughly divided into two categories including volatile memory devices and nonvolatile memory devices. Volatile memory devices lose stored data when disconnected from power and nonvolatile memory devices retain stored data when disconnected from power. Examples of volatile memory devices include static random access memory (SRAM), dynamic random access memory (DRAM), and synchronous dynamic random access memory (SDRAM). Examples of nonvolatile memory devices include read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable and programmable read-only memory (EEPROM), flash memory, phase-change random access memory (PRAM), magnetoresistive random access memory (MRAM), resistive random access memory (RRAM), and ferroelectric random access memory (FRAM).
Among nonvolatile memory devices, flash memory is one of the most widely adopted, with numerous electronic devices using flash memory for long term mass data storage and/or code storage. Examples of devices using flash memory include portable electronic devices, such as digital cameras and smart phones, solid state disks, and so on.
Flash memory has two common configurations presenting distinct performance tradeoffs. These configurations include NOR-type flash memory, which tends to have relatively higher read speed and is therefore useful for storing operating code, and NAND-type flash memory, which tends to have relatively higher integration density, allowing for greater storage capacity.